Ship&#39;s hull



Patented Apr. 28, 1931 narran strates rseazse GNTHER Knivrrnor HAMBURG, GERMANY- .Y

sHIrs HULL Application filed January 14, 1931, Serial No.` 508,739, and Germany Ang'nst 24,192.9.71 i

Efforts to increase the speed, controllability, and so forth, of ships extend both to the shape of the ship and to the accessories thereof, such as steering or rudder appliances and also to the driving means.

The present invention relates to an improvement in the form of the ship for the purpose of shaping the current of water flowing to the rear of the ship uniformly, and thereby preventing the formation of dead water eddies in front of the propeller, increasing the driving eiect of the propeller and obviating disadvantages such' as vibrations, air suction and the like. The idea of the invention is embodied in a definite construction, in which, as compared with the more or less ll-shaped cross sect-ions of the form of the after part of a. ships hull hitherto usual, substantially pear-shaped cross sections are provided in front of the propeller.l For the better understanding of the invention, the generally known form of the after part of a ships hull will first be explained.

In the accompanying drawings, Figures l and 2 are diagrams representing the usual construction of the after part lof a ship, and

Figures 3 and 4 are similar diagrams illustrating the constructionof the after part of a ship accordingto the present invention.

Figure l is a rear end View of a ships hull represented in the manner with which shipbuilders are familiar, and showin@ sections on thelines l, 2, 8, 4, 5, 6 and 7 inCFigure 2.

Planes of section pass through characteristicV positions near the stern of the ship, and are so arranged that the boundary lines are formed by the lines of intersection of the planes of section perpendicular to thekeel plane with the outer skin of the ship.

The lines 8, 9 and 10 represent the characteristic stream lines assumed for the purpose of distinguishing the mean directions of now along which the water iiowing towards the propeller moves. The circles in Figures 1 and 3 represent the circles 4passing through the tips of the propeller blades and the centres of these circles represent the centres of the propeller shafts. The stream line 8 passes through the uppermost point of the propeller circle, parallel to the plane of flotation.; The

stream line 9 is likewise parallel to the axis of the propeller. Underneath the line 9, the direction of flow, as indicated bythe line l0, which is inclinedat an angle of 45O executes an oscillation corresponding to the curvature '55 of the lines 7, 6, 5, and so forth. From the line 9 onwards the directions of How, and the stream lines characterizingthem upon the outer skin extend unitarily tothe centre point of the propeller shaft. K "60 In Figures 2 and 4, three characteristic streamlines S, 9 and l0 are drawn, those in Figure 2 representing the stream lines of the normal. form of ship hitherto known, and thosein Figure 4 representing the stream lines 65 "of the new Aform of hull constructed accord-` ing-to the present invention. Whereas hitherto theinclination of the stream lines in a downward direction from above was variable and became graduallymore acute, the new form is characterized by the feature that all the stream lines have the same inclination. `inthe case of double curves the inclination ofthe tangent at the point of inflection isthe inclinationconsidered.` v

A second feature ofthe new formresides in the 'fact that in the case of the individual streamlines their rpoints of maximumcurvature are uniformly distributed along the lengt-h ofthe ship,so.that the points of maXimum I curvaturev of the lower stream lines lie farther back than those of the yupper stream lines, as indicated in Figure 4 by the numerals 8,9, and 10, which are placed close l to the points of greatest curvature, While in 35 the case of the stream lines of normal form illustrated in Figure 2, these points of maximum curvature are irregularly located at about the same part of the ships length.

The idea of the invention is that by the uniform distribution of the curvatures in the longitudinal direction downwards from above and rearwards from thefront, the formation and separation of eddies of deadwater is prevented, While conversely with an equal position of all the curvatures, as indicated in Figure 2, bythe numerals 8, 9, and 10, such formation and separation is promoted.

The kdistribution of the curvature is therefore physically of lgreat importance as re- 10 gards the resistance formation, because any curvature of form produces an acceleration of the liquid iowing along it and a diminution of pressure by centrifugal action. A. summation of these elfects at the saine place acts injuriously upon the Jformation and resistance and separation of eddies. Y

Hence the object of the invention is to hinder the formation of separation eddies or dead Water eddies at the after part of the ship and to supply to the propeller, While preserving the normal form of stern, water flowing as uniformly as possible, and thus to increase its eiiiciency. Since the invention provides the solution of this problem while taking into consideration the existing normal stern'conditions of single-screw ships, tlieform characterized may also be applied to existing ships by providing a supplementary structure in front of the propeller.

lhat I claim is l rl. A ships hull, so shaped in its after part that of thestreain lines arising on the outer skin of the ship from the horizontal sections through the after part-of the ship vat diiferent heights, those that are uppermost have their maximum curvature farther forward than those beneath them, so that a line joining the points of maximum curvature of the various stream lines shows a displacement of 'these points starting from the top in the front and extending in a downward direction towards the rear.

2. A sliipsvhull as claimed in claim l, the forinof Which is further characterized by the feature that a horizontal stream line passing through the uppermost point of the propeller circle, a horizontal stream line passing through the centre of the propeller circle, and a Astream line passing through the centre point of the propeller circle at an angle of forty-five degrees, all have the saine angle of slope at the centre of the propeller.

In testimony whereof I have signed my nameto this specification.

GNTHER KEMPF. 

